Low energy SIMS characterisation of ultra thin oxides on ferrous alloys

Ultra low energy SIMS was used to create chemical depth profiles of Fe–Cr alloys and stainless steels in order to assess the effect of alloying additions on the surface oxide films. The results have thus far demonstrated that the nanometer scale surface oxide films formed on Fe–Cr alloys are strongly related to the alloy composition and that a critical composition exists corresponding to a change in the oxide chemistry. This composition can be related to differences in electrochemical behaviour of these alloys. This technique allows the effect of individual alloying elements on the surface oxide to be evaluated at previously unavailable depth resolution.